If you're looking for the differences between 45 degree bearing edges, I guess it's ok. There are a multitude of bearing edge styles that aren't mentioned and it doesn't really mention anything about how deep the cuts are. It's a good paper for 45 degree generalities but that's about it.

recording technique is horrible, the results should not be look at seriously. The mics being dynamic only accentuate the low end, and their placement should have resulted in a phase problem. Using 2 microphones to record one sound source is not just setup an call it done. Due to the physical nature of sound waves, and the speed of sound if you are setting up two mics they should be spaced 3 feet apart and at the same distance to avoid phase cancellation. This is known as the "3 to 1 rule" in sound engineering. For what you are trying to achieve, an honest sound of the drum, you should have used one condenser microphone and placed it 6-8inches above the head 1-1 1/2" from the rim. Also micing the shell seems really odd why did you do this? The edges profile should prove enough difference in sound to get your point across, unless you wanted to capture the tiny bit of shell resonance?